Re: [ECOS] DHCP shuts down Ethernet device?

[Jonathan Larmour <jlarmour at redhat dot com>]

Hugo Tyson wrote:
> 
> Grant Edwards <grante@visi.com> writes:
> > I just discovered that when the DHCP task fails to find a
> > server, it then shuts down the Ethernet driver using the code:
> >
> >     // Shut down interface so it can be reinitialized
> >     ifr.ifr_flags &= ~(IFF_UP | IFF_RUNNING);
> >     if (ioctl(s, SIOCSIFFLAGS, &ifr)) { /* set ifnet flags */
> >         perror("SIOCSIFFLAGS down");
> >         return false;
> >         }
> >
> > This generates a call to the _stop() method in the Ethernet
> > driver.
> >
> > I realise that if DHCP fails, the IP stack needs to be shut
> > down, but stopping the ethernet device entirely keeps non-IP
> > stuff from working.  Does the DHCP code assume that there are
> > no non-IP network protocols, or is the above supposed to shut
> > down only IP networking on the device?  The other drivers I've
> > looked at all seem to shut off the interface completely.
> 
> It shuts down everything, deliberately.
> 
> > I think I'm going to have to either comment out the above call,
> > or make my Ethernet driver's _stop() method into a noop...
> 
> Either of those would do.

I'm wondering: isn't the problem just that configuring the interface down
calls the _stop() method? Why not just not do that? The common eth driver
already just has eth_drv_recv() return immediately if the interface is
down. Of course it depends where any non-TCP/IP stack is plugging in...

It probably shouldn't be the default behaviour admittedly, otherwise we're
just doing a bunch of interrupt processing for no reason in the most common
case.

Jifl
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